Like connect-the-dots, but with a side order of crack
Like most puzzle games, the basic gist of Gunpey is easy enough to grasp. Tiles rise up from the bottom of the screen on a timer or at your behest, each stamped with a straight or bent line, and you must vertically swap them to create lines that connect the left and right sides of a 5x10 grid. Lines may fork and zigzag, depending on how you arrange the pieces, but only paths that reach all the way from left to right will disappear.
At first, it seems like play consists of little more than a rush to swap pieces to stranded top-most tiles in an effort to make them disappear before they reach the top of the screen and end the game, but you'll quickly find that skill progression proceeds at an almost subconscious level. You seem to get better the more you play, even if you don't actively seek out the patterns and strategic moves that unlock the true pleasures of Gunpey. Once you commit to the experience, however, you'll find it wraps itself around the primitive, obsessive core of your brain and won't let go. Just... one... more... line. Sure, buddy. You can quit anytime you want.
What keeps Gunpey from being a true new puzzle classic, despite all the Lumines -esque trappings of unlockable skins, varying music, and line-breaking effects, is that the core experience doesn't lend itself to much variety. There are "original" and "break" rule sets that determine whether tiles above a destroyed line fall or not, but that's the only substantive variation on tap. In fact, the only real gameplay difference between one skin and another is the rate at which the tide of tiles rises.